Cry Baby...
Somewhere in the 1960's VOX (Jennings Musical Instruments) created a rocking style foot activated effects pedal. It had a controllable tone circuit that allowed a guitarist emulate the sound of a muted trumpet. As you press the pedal like a car accelerator, it made a 'wah' sound rocking forward and back. Thus the Wah-Wah pedal was born.Innovation leads to copy and many other companies followed with their versions of the wah pedal. I'm not sure of the patent rights, but I know each company had to be different enough to avoid lawsuits. A lot has happened over the years and one of the most famous wah pedals are manufactured by Dunlop. Their precise circuit tuning can make a guitar sound like it's crying... because of this, it's called the CRY BABY.
Demo of the pedal: